All EF mounts ordered with lenses will be calibrated to each lens and will come with the correct total shim thickness marked on the inside of the mount.
All shims are stainless steel and are stamped with their thickness value for easy recognition.
Mounts can be easily changed with the recommended number of shims (marked on the inside of each mount) and a T6 Torx driver in a clean environment. Please take care to use the mount shim thickness indicated.
For instructions on how to swap out mounts, please see the Orion Series Owner’s Manual (page 7).